Wilhelm deckert



mammal.)

W, DECKERT.

MICROPHONE.

No. 517,564. Patented Apr. 3, 1894.

s milla #IIIIIIII llnirrn raras muon.

ArnNr MICROPHONE.

SPECIFICATION forming part of Letters Patent No. 517,564, dated April 3, 1894.

Application led March l, 1893. Serial No. 464,259. (No model.) Patented inrI'rance November 28, 1891, No. 217,736; in England December 9, 1891, No. 21,565I and in Austria-Hungary March 7, 1892, No; 49,855 and No. 2,654.

.To all whom 111'; may concern,.-

Be it known that I, WILHELM DnoKER'r, a subject of the Emperor of'Austria-Hungary,

Yresiding at Vienna, Austria-Hungary, have invented certain new and useful Improvements in Microphones, (for which I have obtained patents in Austria-HungaryLNo. 49,855 and No. 2,654, dated March 7, 1892; in France, No.

microphones, and has for its object the construction of an improved microphone transmitter of this kind.

In the annexed drawings, in which I have shown a microphone constructed according to my invention Figure 1 shows the same in side elevation, partly in section, and Figs. 2, 3, 4, 5 and 6 show details thereof.

In all figures similar letters of reference indicate corresponding parts.

My improved microphone essentially consists of a diaphragm or membrane ctheld or clamped in a casing b by a cover, to which a mouthpiece d is screwed or attached in any other suitable manner.

In the opening of` cover c, between the latter and mouthpiece d is placed and held a disk of netting, by preference of metal, suitably protected against oxidation by a coating of gold, silver, nickel, varnish or any other suitable substance. This Vdisk of netting c may also be made of any other non-hydroscopic fabric. The'important object of this protective netting eis to prevent, in speaking, the condensationof the breath upon the diaphragm when the latter is cold, to prevent saliva and particles of food from the mouth reaching the diaphragm, so as to keep the latter dry and sensitive to the least waves of sound, and finally to protect the diaphragm also against mechanical injuries. This netting also offers advantages in a hygienical point of view, as it can easily be removed and cleaned or exchanged. The transmission of l sound is in a very slight degree influenced by the interposition of this netting, but this imperceptible loss becomes insignificant compared with the great advantages the netting offers.

Diaphragm a (Figs. 1, 5 and 6) is made of electric conducting material, as for instance metal, but by preference I make the same of carbon. The surface of diaphragm a, facing the mouthpiece, is covered with a coating of varnish ,for protecting it against moisture, while the other inner surface is covered with a layer f of elastic, insulating material, such as cotton, wool, hair or such like, only leaving the central part of. of the diaphragm free for electric contact. This felting or covering of the entire inner surface of the diaphragm with the exception of the conducting central part thereof has the object, in speaking, to utilize only the strongest waves of sound, and

' this elastic coating further absorbs or collects the carbon dust vformed in the microphone,l

which otherwise would disturb the proper operation of the latter., Coating f of the diaphragm also serves to prevent the sagging or settling of the granules of carbon, which in the vertical employment of the apparatus of this kind generally takes place by the own weight of the carbon grains. By preventing this in the manner described the resistances in the microphone remain constant, and an always clear reproduction of the sounds is obtained. Coating f finally acts as a damper, and for-ms a tight joint between casing b and cover c, and prevents short circuiting in the vmicrophone by not permitting the carbon number of diamond points, which I form by preference by cutting V shaped grooves across the surface of the electrode in one direction, and by intersecting these grooves by short alternate grooves of similar shape, so' as to 'form the diamond points shownin Fig. 3.

The points coming in juxtaposition with the conducting part a of the diaphragm are hol- 4lowed out or provided with crater-shaped The elec-A IOO ducting part a' of the diaphragm so lightly as not to influence the vibrations of the latter in any perceptible degree, serve as dampers for excessive undulations caused by very strong sound waves, but their main object is to prevent any jamming of carbon grains between the electro points and the diaphragm. Thespace between the diamond pointed face of the electrodeandthe diaphragm islled with carbon grains fi. Electrode g is held in a body or box k of non-conducting material, inclosed in casing b, by preference by ascrew Z. Box 7c also carries the two binding screws 7i and p, of which pisin electric connection with screw Z and electrode g by means of a wire m, and n in electric connection with diaphragm a by a' wire o.

What I claim, and desire to secure by Let ters Patent, is

l. In grainor powdermicrophones the combination with a box or casing, a cover, and a mouth piece attachedthereto,of diaphragm a of electric conducting material, covered on its side facing the mouthpiece with a protective coating against moisture, and on its other side with a coating of elastic non-conducting material f, leaving an uncovered conducting surface a', and of an electrode g; substantially as and for the purpose described.

2. In grainor powdermicrophones the 3o combination with a box or casing a cover and a mouthpiece attached thereto of diaphragm a, an electrode g with alternately placed diamond points facing the diaphragm, and of tufts or brushes h of elastic non-conducting material attachedto the diamond points oppo- A 

